Benchmarking of Grid Fault Modes in Single-Phase Grid-Connected Photovoltaic Systems

Abstract

Pushed by the booming installations of singlephase photovoltaic (PV) systems, the grid demands regarding the integration of PV systems are expected to be modified. Hence, the future PV systems should become more active with functionalities of Low Voltage Ride-Through (LVRT) and grid support capability. The control methods, together with grid synchronization techniques, are responsible for the generation of appropriate reference signals in order to handle ride-through grid faults. Thus, it is necessary to evaluate the behaviors of grid synchronization methods and control possibilities in single phase systems under grid faults. The intent of this paper is to present a benchmarking of grid fault modes that might come in future single-phase PV systems. In order to map future challenges, the relevant synchronization and control strategies are discussed. Some faulty modes are studied experimentally and provided at the end of this paper. It is concluded that there are extensive control possibilities in single-phase PV systems under grid faults. The Second Order General Integral based PLL technique might be the most promising candidate for future single-phase PV systems because of its fast adaptive-filtering characteristics and it is able to fulfill future standards.

Coordinated Control of Superconducting Fault Current Limiter and Superconducting Magnetic Energy Storage for Transient Performance Enhancement of Grid-Connected Photovoltaic Generation System

“…The VSC and the chopper use the standard models from the MATLAB model library, and the superconducting magnet is simulated by a non-resistive inductance model. For the specific FRT code which the PV generation system should follow, the Denmark code is selectively used in the simulations [68]. In the case of that the grid voltage drops to 20% of the nominal level, the PV generation system should remain the grid-connected state for a duration of 150 ms.…”

Technical Evaluation of Superconducting Fault Current Limiters Used in a Micro-Grid by Considering the Fault Characteristics of Distributed Generation, Energy Storage and Power Loads

“…It is assumed that the SC will enter the quenching state within 4 ms, and after the short-circuit fault is removed, the SC's recovery time is set as 0.5 s to cooperate with the reclosing. As shown in Figure 8, different FRT curves of a defined stay-connected time for IIDG are indicated [48,49]. From this figure, the FRT requirement differs from one standard to the other based on the countries' grid code.…”

“…From this figure, the FRT requirement differs from one standard to the other based on the countries' grid code. During the simulations, the Denmark code is selectively used, and in the case that the grid voltage drops to 20% of the nominal level, the IIDG should remain in the grid-connected state for a duration of 150 ms. As shown in Figure 8, different FRT curves of a defined stay-connected time for IIDG are indicated [48,49]. From this figure, the FRT requirement differs from one standard to the other based on the countries' grid code.…”

Zero-Voltage Ride-Through Capability of Single-Phase Grid-Connected Photovoltaic Systems

“…In summary, it is expected that the grid-friendly PV systems should be multiple-functional. That is, for instance, reactive power control, maximum power point tracking (MPPT), fault islanding detection, harmonic compensation, and fault ride-through (FRT) operation are required for PV systems [4][5][6][7][8][9][10][11][12][13][14]. Actually, some PV power systems…”

“…The conventional dual-loop control structure in single-phase PV systems could be applied under the grid fault by directly calculating the current references [30]. When the instantaneous power theory is adopted in single-phase PV systems, the single-phase instantaneous active and reactive powers (PQ) theory [31] can be used to independently control the active and reactive power under LVRT as reported in [11][12][13][14]. In addition, the droop control methods could be considered as an alternative for regulating the active and reactive power under the grid fault [32], on condition that the grid is mainly inductive.…”